Abstract

In the wake of global warming and dwindling oil resources, renewable green energy needs to be developed in order to maintain current standards of living. One of the most promising green energy sources is solar energy due to its sheer abundance and ubiquity. However, in order for the solar cells of tomorrow to become a serious competitor in the energy market, efficiency needs to be increased and production costs have to be reduced. This is the essence of light trapping.

In this study, the light trapping effect of anti-reflection coatings (ARC) on solar cells were investigated. First a theoretical approach is undertaken and the optimal parameters for ARC design are determined. Experiments are then undertaken to examine this theoretical approach. Multiple test samples of single-layered ARC were fabricated with various properties and thickness, and their abilities to improve photon trapping were measured and calculated. An additional test sample of a double-layered ARC is also produced in order to investigate the effects of having multiple layers compared to a single layer. A test sample where ARC is applied on textured silicon has also been fabricated in order to investigate what the effects of combining two ways of decreasing reflection has on light trapping potential. All experiments were conducted with normal angle of light incidence.

This investigation concluded that the most important feature for ARC design is to have low reflectance around the wavelength range which corresponds to peak photon flux of the solar spectrum. This is achievable for single-layered ARC when the refractive index is the geometric mean of substrate and superstrate and the thickness is adjusted to allow for complete destructive interference between reflected and incoming waves. Multi-layer ARC and surface-texturing of the silicon substrate decrease reflectance across a wider range of wavelengths allowing for better overall performance.